Rotating machine

ABSTRACT

The rotating machine includes a rotating shaft, a case surrounding the rotating shaft, the case being provided with a fluid storing chamber and formed with a housing section. The rotating machine further includes a bearing disposed in the housing section and supporting the rotating shaft, and a ring-like seal member disposed between the fluid storing chamber and the bearing for suppressing the fluid from flowing through a clearance between the rotating shaft and the case. The case is formed with a drain hole for making communication between atmosphere and a space surrounded by the seal member and the bearing within the case and discharging the fluid leaking from the fluid storing chamber and passing the seal member to enter the space, and an atmosphere introducing hole for introducing outside air into the space to keep the space at atmospheric pressure.

This application claims priority to Japanese Patent Application No. 2011-267137 filed on Dec. 6, 2011, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rotating machine provided with a seal member disposed surrounding its rotating shaft.

2. Description of Related Art

Japanese Patent Application Laid-open No. 2008-49743 describes a rotary pump apparatus as a rotating machine provided with a seal member for preventing fluid from flowing through a clearance between its rotating shaft and its case which surrounds the rotating shaft, and a bearing supporting the seal member and the rotating shaft. This rotary pump apparatus is accommodated in a metal housing which constitutes an actuator for brake fluid pressure control, and configured to drive two rotary pumps accommodated in the case using one rotating shaft. In this rotary pump apparatus, the rotating shaft is supported by the bearing at the rear side of the case. An oil seal as a seal member is disposed surrounding the rotating shaft at more inside of the case than the bearing to prevent brake fluid from leaking from the side of the rotary pumps through a clearance between the case and the rotating shaft.

However, the provision of such an oil seal as described in the above patent document cannot completely suppress the brake fluid leakage through the clearance between the case and the rotating shaft. Accordingly, it may occur that the brake fluid passes the oil seal, leaks toward the bearing and further flows outside the bearing, as a result of which the grease filled in the bearing is washed out disturbing smooth rotation of the bearing. Therefore, it is necessary to take some measures to prevent the grease of the bearing from being washed out even when the brake fluid passes the oil seal and leaks toward the bearing.

The above problem may occur in any rotating machine having a chamber storing fluid accommodated in a case, a rotating shaft penetrating through the chamber, and a seal member provided for suppressing the fluid from leaking from the chamber through a clearance between the case and the rotating shaft.

SUMMARY

An exemplary embodiment provides a rotating machine including:

a rotating shaft;

a case surrounding the rotating shaft, the case being provided with a fluid storing chamber for storing fluid and formed with a housing section disposed more outside in an axial direction of the rotating shaft than the fluid storing chamber;

a bearing supporting the rotating shaft, the bearing being disposed in the housing section, having an inner race, an outer race and a plurality of rolling bodies disposed between the inner and outer races, and being filled with grease; and

a ring-like seal member disposed between the fluid storing chamber and the bearing within the housing section for suppressing the fluid from flowing through a clearance between the rotating shaft and the case,

wherein

the case is formed with a drain hole disposed at a position below an axial center of the rotating shaft for making communication between atmosphere and a space surrounded by the seal member and the bearing within the case, and discharging the fluid leaking from the fluid storing chamber and passing the seal member to enter the space, and

an atmosphere introducing hole for introducing outside air into the space to keep the space at atmospheric pressure.

According to the exemplary embodiment, there is provided a rotating machine capable of suppressing fluid stored in a fluid storing chamber provided in a case thereof from leaking through a clearance between its rotating shaft and the inner wall of the case, and suppressing grease filled in a bearing supporting the rotating shaft from being washed out even if the fluid leaks and flows toward the bearing.

Other advantages and features of the invention will become apparent from the following description including the drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a partially enlarged diagram showing a partial cross-section of a rotating machine according to an embodiment of the invention;

FIG. 2 is a partial enlarged diagram of a part of FIG. 1 surrounded by the chain line; and

FIGS. 3A and 3B are cross-sectional views of the part shown in FIG. 2 for comparison between different positional relationships between a drain hole 4 e and a chamfered portion of this part.

PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 is a partially enlarged diagram showing a partial cross-section of a rotating machine 1 according to an embodiment of the invention. FIG. 2 is a partially enlarged diagram of a part of FIG. 1 surrounded by the chain line. The vertical direction (up-down direction) and the horizontal direction shown in FIG. 1 correspond to those of the rotating machine 1 when it is installed in place.

As shown in FIG. 1. the rotating machine 1 includes a rotating shaft 3 coupled to a drive shaft (not shown) of a motor 2, a case 4 formed with a center hole 4 b in communication with a fluid chamber 4 a for storing fluid.

The rotating machine 1 is fixed to a metal housing 5 by being inserted into an insertion hole 5 a formed in the housing 5. In the following, the direction in which the rotating machine 1 is inserted into the insertion hole 5 a is referred to as the inserting direction. The rotating machine 1 may be a rotary pump apparatus, for example. In a case where the rotating machine 1 is a rotary pump apparatus, the rotating machine 1 may be disposed in a brake fluid control actuator. In this case, the fluid storing chamber 4 a is used as a chamber for accommodating two rotary pumps, and the rotating machine 1 is used to control the pressure of the brake fluid supplied to a wheel cylinder through a brake pipe.

The rotating shaft 3 of the rotating machine is supported by a bearing 6 disposed at the rear end of the case 4 on the side of the motor 2, and more particularly, at the more rear side of the case 4 in the inserting direction than the fluid storing chamber 4 a. The case 4 is bored with a housing section 4 c whose inner diameter is made larger than that of the rotating shaft 3 at its rear portion in the inserting direction. The bearing 6 is disposed in the housing section 4 c. That is, the bearing 6 is fitted in the housing section 4 c formed more axially outside than the fluid storing section 4 a.

The bearing 6 is not limited to any particular structure. In this embodiment, a narrow width ball bearing is used as the bearing 6. More specifically, the bearing 6 includes an inner race 6 a, an outer race 6 b and rolling bodies 6 c disposed between the inner and outer races 6 a and 6 b. Grease (not shown) is filled between the inner and outer races 6 a and 6 b. The rotating shaft 3 is supported by the bearing 6 in such a condition that the outer race 6 b is inserted and fixed into the housing section 4 c of the case 4, and the rotating shaft 3 is fitted in the hole of the inner race 6 a.

The bearing 6 includes also seal plates 6 d. The seal plates 6 d are disposed on both axial ends of the inner and outer races 6 a and 6 b to shield between the space surrounded by inner and outer races 6 a and 6 b and the space 8 surrounded by the bearing 6 and a later described seal member 7, and to shield between the bearing 6 and the outside. Since the bearing 6 is disposed on the rear side in the inserting direction, the provision of the seal plates 6 d makes it possible to suppress the brake fluid (may be referred to simply as the fluid hereinafter) leaking from the fluid storing chamber 4 a from further leaking outside through the bearing 6.

The seal member 7 having a ring shape is disposed surrounding the rotating shaft 3 at the more front side of the case 4 in the inserting direction than the bearing 6, that is, at the side of the fluid storing section 4 a. Also the seal member 7 is disposed in the housing section 4 c of the case 4. The seal member 7 and the bearing 6 are inserted and fitted into the housing section 4 c in this order.

The seal member 7 is constituted of a metal plate 7, an elastic member 7 b and a coil spring 7 c. The metal plate 7 a, which has a ring shape, is formed integrally with the elastic member 7 b. The elastic member 7 b is a ring member whose cross section is V-shaped extending toward the bearing 6, and is in contact with at least the inner wall of the case 4 and the outer periphery of the rotating shaft 3. The coil spring 7 c produces elastic force pressing the elastic member 7 b against the rotating shaft 3. By the provision of the seal member 7 having the above described structure, the clearance between the case 4 and the rotating shaft 3 is sealed to suppress the fluid stored in the fluid storing section 4 a from flowing toward the bearing 6 through the clearance between the case 4 and the rotating shaft 3.

The diameter of the housing section 4 c of the case 4 is reduced at a portion in which the bearing 6 is disposed. The seal member 7 is fitted in this diameter-reduced portion. The boundary portion between the diameter-reduced portion and the portion in which the bearing 6 is disposed is tapered to have a tapered surface 4 d. The slope of the tapered surface 4 d facilitates inserting the seal member 7.

As described above, since the seal member 7 is disposed between the bearing 6 and the fluid storing chamber 4 a, it is possible to suppress the fluid stored in the fluid storing chamber 4 a from leaking into the space 8 surrounded by the seal member 7 and the bearing 6. However, since the sealing function of the seal member 7 cannot completely suppress the fluid leakage, some amount of the fluid stored in the fluid storing chamber 4 a may leak into the space 8. To discharge the leaked fluid outside the rotating machine 1, the case 4 is formed with a drain hole 4 e in communication with the space 8 and an atmosphere introducing hole 4 f.

The drain hole 4 e is located below the center of the rotating shaft 3 within the case 4. The drain hole 4 e may be a circular hole formed by drilling processing so as to extend in the radial direction of the rotating shaft 3. The drain hole 4 e is required to be in communication with the space 8 and located at the side closer to the bearing 6 than the sealing portion between the seal member 7 and the inner wall of the case 4. In this embodiment, as shown in FIG. 2, the drain hole 4 e is formed such that the front end of bearing 6 on the side of the seal member 7 is beyond the edge P of the drain hole 4 e on the side of the bearing 6 to be within the drain hole 4 e, and the drain hole 4 e overlaps with the tapered surface 4 d.

The atmosphere introducing hole 4 f is for keeping the space 8 at the atmospheric pressure by being in communication with the space 8. The atmosphere introducing hole 4 f may be formed in any portion of the case 4 to introduce the outside air which is unlikely to be blocked by the fluid leaking while passing through the seal member 7. In this embodiment, the atmosphere introducing hole 4 f is formed above the rotating shaft 3. Also the atmosphere introducing hole 4 f is a circular hole formed by drilling processing so as to extend in the radial direction of the rotating shaft 3.

When the drain hole 4 e and the atmosphere introducing hole 4 f have the same diameter, they can be formed using the same drill to streamline the manufacturing process. For example, when they are located at 180 degree opposite positions across from the rotating shaft 3, they can be formed by one time drilling processing. When they are not located at 180 degree opposite positions across from the rotating shaft 3, they can be formed in succession by turning the case 4 around the axial center of the rotating shaft 3. The drain hole 4 e and the atmosphere introducing hole 4 f does not necessarily have to have the same diameter. However, the drain hole 4 e is required to have a sufficiently large diameter so as not to be closed by a film of the brake fluid, and the atmosphere introducing hole 4 f is required to be capable of introducing sufficient amount of the outside air.

As explained above, the rotating machine 1 of this embodiment has the structure in which the drain hole 4 e is formed so as to be in communication with the space 8 between the bearing 6 and the seal member 4 within the case 4. Accordingly, even if the fluid stored in the fluid storing chamber 4 a passes the seal member 7 and leaks into the space 8, this fluid can be discharged through the drain hole 4 e. Further, since the atmosphere introducing hole 4 f is provided so that the space 8 can be kept at the atmospheric pressure, even if the fluid closes the drain hole 4 e, it is possible to reliably discharge the fluid through the drain hole 4 e.

Incidentally, the provision of the atmosphere introducing hole 4 f contributes to reducing the size of the rotating machine 1. If the atmosphere introducing hole 4 f is not provided, the inner diameter of the drain hole 4 e has to be made large enough not to be closed by an oil film of the brake fluid. In this embodiment, since the atmosphere introducing hole 4 f is provided, the inner diameter of the drain hole 4 e can be made smaller while preventing an oil film of the brake fluid from being produced. Hence, according to this embodiment in which the atmosphere introducing hole 4 f is provided, it is possible to reduce the inner diameter of the drain hole 4 e, and accordingly reduce the size of the rotating machine 1.

Further, according to this embodiment in which the seal member 7 suppresses the fluid stored in the fluid storing section 4 a from leaking through the clearance between the case 4 and the rotating shaft 3, it is possible to suppress the grease filled in the bearing 6 from being washed out even if the fluid passes the seal member 7 and leaks toward the bearing 6. Further, also the fluid passing the bearing 6 and the grease washed out from the bearing 6 can be suppressed from entering inside the motor 2.

In the rotating machine 1 of this embodiment, the bearing 6 is provided with the seal plates 6 d. The provision of the seal plates 6 d further suppresses the fluid from entering inside the bearing 6 to further suppress the grease filled in the bearing 6 from being washed out. However, the provision of the seal plates 6 d cannot completely suppress the fluid from entering inside the bearing 6, if there is no way out for the fluid passing the seal member 7 and entering the space 8. In this embodiment, since both the drain hole 4 e and the atmosphere introducing hole 4 f are provided, even if the fluid passes the seal member 7 and flows toward the bearing 6, it is possible to still further prevent the grease filled in the bearing 6 from being washed out.

As shown in FIG. 2, the end of the outer race 6 b of the bearing 6 on the side of the seal member 7 projects inside the drain hole 4 e. If the end surface of the outer race 6 b on the side of the seal member 7 is located closer to the side opposite the seal member 7 than the edge of the drain hole 4 e on the side of the bearing 6 in the axial direction of the rotating shaft 3, the inner wall of the housing section 4 c intervenes by an amount corresponding to the distance therebetween between the end surface of the outer race 6 b and the edge of the drain hole 4 e. In this case, the fluid leaking from the fluid storing chamber 4 a into the space 8 adheres to the end surface of the bearing 6, and drops downward from the end surface, as a result of which the fluid adheres to the lowermost portion of the curved surface of the inner wall of the housing section 4 c parallel to the axial direction of the rotating shaft, and easily accumulates there by surface tension. According to this embodiment having the above described structure, it is possible to sufficiently reduce the portion of the inner wall of the housing section 4 c, which intervenes between the end surface of the outer race 6 b and the edge of the drain hole 4 e. Hence, the liquid leaking from the liquid storing chamber 4 a into the space 8 can easily reach the drain hole 4 e and be easily discharged through the drain hole 4 c.

The above described advantageous effects can be obtained when the position of the end surface of the outer race 6 b of the bearing 6 on the side of the seal member 7 coincides with the position of the edge (shown by P in FIG. 2) of the drain hole 4 e on the side of the bearing 6, or projects inside the opening of the drain hole 4 e. However, the outer edge of the outer race 6 b may be chamfered at the position of the end of the bearing 6. In this case, it is preferable that the portion to be chamfered is located inside the opening of the drain hole 4 e as shown in FIG. 3A. This is because if the position of the end of the bearing 6 on the side of the seal member 7 is too close to or coincides with the position of the edge of the drain hole 4 e on the side of the bearing 6 as shown in FIG. 3B, it is probable that a hollow is made between the chamfered portion and the inner wall of the housing section 4 c, and the fluid enters in this hollow to disturb the flow of the fluid. Accordingly, if the portion to be chamfered is located inside the drain hole 4 e to eliminate such a hollow, the fluid can flows into the drain hole 4 e smoothly.

In this embodiment, the drain hole 4 e is formed so as to overlap with the tapered surface 4 d. This makes it possible that the fluid passing the seal member 7 can flow into the drain hole 4 e smoothly before reaching the lowermost portion of the curved surface of the inner wall of the housing section 4 c which is parallel to the axial direction of the rotating shaft.

Incidentally, the discharged fluid is stored in a not shown fluid reservoir. The fluid passage may be formed by forming a clearance between the housing 5 and the case 4 or between the housing 5 and the motor 2, or forming a hole in the housing 5.

Other Embodiments

It is a matter of course that various modifications can be made to the above embodiment as described below.

In the above embodiment, the seal member 7 is constituted of the metal plate 7 a, the resilient member 7 b and the coil spring 7 c. However, the seal member 7 may be any ring-like seal member capable of sealing between the rotating shaft 3 and the case 4. The rotating machine 1 described above is a rotary pump apparatus. However, the present invention is applicable to any rotating machine which needs a ring-like seal member for suppressing fluid from flowing through a clearance between a rotating shaft and a case thereof and a bearing supporting the rotating shaft.

The above explained preferred embodiments are exemplary of the invention of the present application which is described solely by the claims appended below. It should be understood that modifications of the preferred embodiments may be made as would occur to one of skill in the art. 

What is claimed is:
 1. A rotating machine comprising: a rotating shaft; a case surrounding the rotating shaft, the case being provided with a fluid storing chamber for storing fluid and formed with a housing section disposed more outside in an axial direction of the rotating shaft than the fluid storing chamber; a bearing supporting the rotating shaft, the bearing being disposed in the housing section, having an inner race, an outer race and a plurality of rolling bodies disposed between the inner and outer races, and being filled with grease; and a ring-like seal member disposed between the fluid storing chamber and the bearing within the housing section for suppressing the fluid from flowing through a clearance between the rotating shaft and the case, wherein the case is formed with a drain hole disposed at a position below an axial center of the rotating shaft for making communication between atmosphere and a space surrounded by the seal member and the bearing within the case, and discharging the fluid leaking from the fluid storing chamber and passing the seal member to enter the space, and an atmosphere introducing hole for introducing outside air into the space to keep the space at atmospheric pressure.
 2. The rotating machine according to claim 1, wherein an end surface of the outer race on the side of the seal member coincides with an edge of the drain hole on the side of the bearing or projects inside an opening of the drain hole.
 3. The rotating machine according to claim 1, wherein an outer periphery of the outer race of the bearing on the side of the seal member is chamfered to have a chamfered portion, the chamfered portion being located inside the opening of the drain hole.
 4. The rotating machine according to claim 1, wherein the bearing includes a seal plate for sealing between a space surrounded by the inner and outer races and the space surrounded by the seal member and the bearing.
 5. The rotating machine according to claim 1, wherein the housing section is a circular bore formed in the case having an inner diameter larger than a diameter of the rotating shaft, the seal member and the bearing are fitted into the housing section in succession, the inner diameter of the housing section is reduced at a diameter-reduced portion thereof portion in which the seal member is disposed, and the case is tapered to have a tapered surface at a boundary between the diameter-reduced portion and a portion in which the bearing is disposed, the tapered surface overlapping with the drain hole.
 6. The rotating machine according to claim 1, wherein the drain hole and the atmosphere introducing holes are circular holes having the same diameter. 